Tesla CEO Elon Musk on Friday announced the addition of a titanium shield and multiple aluminum deflectors to the undercarriage of their Model S to help cut down on the risk of battery fires caused by running over objects on the road.

It’s a real concern as a handful of Model S vehicles have caught fire in recent memory after striking metallic objects in the roadway at highway speeds. Fortunately, nobody has been injured or killed in those accidents but the National Highway Traffic Safety Administration (NHTSA) did launch an investigation into the matter.

Musk noted his company tested the new shields 152 times by running over objects like a concrete block, a steel alternator and a three ball tow hitch. In every test, the shields prevented any damage that could cause a fire.

Musk said the added weight of the shields only have a 0.1 percent impact on range and don’t affect ride or handling. Furthermore, wind tunnel testing shows no discernible change in drag or lift on the car.

All cars manufactured as of March 6 have been outfitted with the new underbody protection. What’s more, the company is offering to retrofit the shields to existing cars upon request free of charge. It’s not a recall as the car maker isn’t being required by the government to make changes but it certainly functions like one.

As such, the NHTSA has closed their investigation into the previous fires.